It is well known to drill holes in bones in order to accommodate fastening devices used to anchor implants within a patient's body. For instance, pedicle screws have been used to anchor instrumentation systems to the spinal column of patients for correcting a variety of spinal disorders. One commonly used technique for inserting a pedicle screw into the bone includes the preparation of a pilot hole through the pedicle before inserting the screw therein. Typically, the selection of the insertion point is made based on the anatomy of the vertebra. Once the insertion point has been selected, a drill guide may be used to guide the drill bit along the proper axis, and/or to set the depth to which the drill bit penetrates the bone. Conventional drill guides generally include a handle having an adjustable length sleeve attached thereto. When used in conjunction with a drill bit having a fixed stop, the length of the sleeve may control the depth to which the drill penetrates the bone (and the depth of the consequent hole). Known drill guides, however, may include one or more drawbacks. For example, it may be necessary to rotate or screw an inner sleeve within an outer sleeve (or other member) to adjust the hole depth. This process can be timely, and may require removing the drill guide from the incision in order to make subsequent adjustments. Known drill guides may also lack any type of incremental adjustment of the hole depth, which may also add to the time required for the adjustment process. In addition, with known drill guides, one or more parts necessary to adjust the hole depth may be located in the patient, thus requiring the drill guide to be removed from the incision in order to adjust the hole depth. Further, known drill guides are often complicated to adjust. Thus, there remains a need in the art for surgical drill guides that provide quick and easy adjustment of the hole depth, allow for such adjustment from outside of the patient, can be left in place during adjustment of the hole depth, and are ergonomic, aesthetically pleasing, and easy to use.